Inhibitory effects of propiverine on rat and guinea-pig urinary bladder muscle

Summary In muscle strips isolated from guinea-pig and rat urinary bladder, propiverine (3–10 M) inhibited carbachol-induced contractions in the presence of verapamil and Ca²⁺-induced contractions in excess K⁺ medium containing atropine, suggesting it has both anticholinergic and Ca²⁺ channel blocking actions.The Ca²⁺ channel blocking action was also demonstrated by recording inward Ca ²⁺ currents in single cells dispersed from both species. The inhibition of inward currents by propiverine was three times stronger in the rat than the guinea-pig, ID₅₀ being 7 M for rat and 21 M for guinea-pig. The recovery of the current after washout was faster than that of mechanical inhibition. It is concluded that propiverine blocks not only muscarinic receptors, but also Ca²⁺ channels at similar concentrations.Correspondence to: T. Tomita at the above address